Ever since I got my laptop( 1 1/2 yrs, I think), I'm unable to record streaming audio in stereo using Audacity. Perhaps my soundcard won't allow it? I find that hard to believe, but I've tried everything & it doesn't work. It ends up sounding "tinny". If anyone can help me with this, I'd greatly appreciate it!
You could have hit the nail there.
Some Thinkpads (like my W500

) won't allow digital sound output over the "Display Port" output or internally to Audacity via "stereo mix".
It's something to do with daft DRM enforcement.
There are other manufacturers machines with the same limitations, the internal audio (stereo mix) disabled, search to see whether yours is one.
If it sounds "tinny" maybe you're in luck and it's just settings related, or you may just be recording via the internal mic.
HTH